Electrode Materials For Secondary Batteries Research Articles

Electrochemical sodium storage properties in monolayer VOPO4: A density functional theory prediction

The unique structural properties of two-dimensional materials make them promising for energy storage applications. This work theoretically predicts for the first time that Monolayer VOPO4 (MNL VOPO4), exfoliated from the delithiated phase of tetragonal LiVOPO4, is stable at room temperature, exhibiting excellent thermodynamic and kinetic stability, thus making it a promising high-capacity anode material for sodium-ion batteries (SIBs). Compared to bulk VOPO4, the monolayer structure significantly reduces the sodium ion migration energy barrier from 1.006 to 0.0795 eV, thereby markedly enhancing sodium ion migration kinetics. MNL VOPO4 can adsorb up to 32 sodium ions, corresponding to a theoretical capacity of 634.88 mA h g−1 and an energy density of 895.18 Wh kg−1. Furthermore, the excellent structural stability of MNL VOPO4 favors its cycling performance during charge and discharge processes. This work provides theoretical insights for better utilizing and developing multi-atomic phosphate compounds as electrode materials for secondary batteries.

Biomass-Derived Carbon Materials for Electrochemical Energy Storage.

The environmental impact from the waste disposal has been widely concerned around the world. The conversion of wastes to useful resources is important for the sustainable society. As a typical family of wastes, biomass materials basically composed of collagen, protein and lignin are considered as useful resources for recycle and reuse. In recent years, the development of carbon material derived from biomasses, such as plants, crops, animals and their application in electrochemical energy storage have attracted extensive attention. Through the selection of the appropriate biomass, the optimization of the activation method and the control of the pyrolysis temperatures, carbon materials with desired features, such as high-specific surface area, variable porous framework, and controllable heteroatom-doping have been fabricated. Herein, this review summarized the preparation methods, morphologies, heteroatoms doping in the plant/animal-derived carbonaceous materials, and their application as electrode materials for secondary batteries and supercapacitors, and as electrode support for lithium-sulfur batteries. The challenges and prospects for the controllable synthesis and large-scale application of biomass-derived carbonaceous materials have also been outlooked.

Precise synthesis of BN embedded perylene diimide oligomers for fast-charging and long-life potassium-organic batteries.

Replacing the C[double bond, length as m-dash]C bond with an isoelectronic BN unit is an effective strategy to tune the optoelectronic properties of polycyclic aromatic hydrocarbons (PAHs). However, precise control of the BN orientations in large PAH systems is still a synthetic challenge. Herein, we demonstrate a facile approach for the synthesis of BN embedded perylene diimide (PDI) nanoribbons, and the polarization orientations of the BN unit were precisely regulated in the two PDI trimers. These BN doped PDI oligomers show great potential as organic cathodes for potassium-ion batteries (PIBs). In particular, trans-PTCDI3BN exhibits great improvement in voltage potential, reversible capacities (ca. 130 mA h g-1), superior rate performance (19 s to 69% of the maximum capacity) and ultralong cyclic stability (nearly no capacity decay over 30 000 cycles), which are among those of state-of-the-art organic-based cathodes. Our synthetic approach stands as an effective way to access large PAHs with precisely controlled BN orientations, and the BN doping strategy provides useful insight into the development of organic electrode materials for secondary batteries.

Multi-structure hollow nanofibers electrode materials for secondary batteries

Multi-structure hollow nanofibers electrode materials for secondary batteries

Polyoxometalates (POMs) with Ion/Electron‐Sponge Properties and Abundant Active Sites as Emerging Electrode Materials for Secondary Batteries: A Review

AbstractFaced with the increasingly severe energy and environment issues, eco‐friendly and efficient energy storage/transformation technology has become a research hotspot. Due to the ion/electron‐sponge properties and superior catalytic performance, polyoxometalates (POMs) have broad prospects in improving the performance of electrodes and batteries. In this paper, the structural characteristics and physical/chemical properties of POMs are introduced, and the recent research progresses of POM‐electrodes for various battery systems are reviewed. By analyzing the relationship between the composition, structure and electrochemical performance of POMs, the advantages and challenges of applying POMs as electrode materials are explained, and the practical modification strategies for improving the performance of POM‐electrode are proposed, aiming to provide reference for the further investigation and application of POMs in energy storage field.

Vanadium Hexacyanoferrate as a High-Capacity and High-Voltage Cathode for Aqueous Rechargeable Zinc Ion Batteries

Prussian blue analogs (PBAs) are widely used as electrode materials for secondary batteries because of their cheapness, ease of synthesis, and unique structural properties. Nevertheless, the unsatisfactory capacity and cyclic stability of PBAs are seriously preventing their practical applications. Here, vanadium hexacyanoferrate (VHCF) is successfully prepared and used as a cathode for aqueous zinc-ion batteries (AZIBs). When using 3 M Zn(CF3SO3)2 as the electrolyte, a high capacity of ~230 mA h g-1 and a high voltage of ~1.2 V can be achieved. The XRD result and XPS analysis indicate that the outstanding Zn2+ storage capability is due to the presence of dual electrochemical redox centers in VHCF (Fe2+ ⇋ Fe3+ and V5+ ⇋ V4+ ⇋ V3+). However, the battery shows a short cycle life (7.1% remaining capacity after 1000 cycles) due to the dissolution of VHCF. To elongate the cycle life of the battery, a high-concentration hybrid electrolyte is used to reduce the activity of water molecules. The improved battery exhibits an impressive capacity of 235.8 mA h g-1 and good capacity retention (92.9%) after 1000 cycles.

Zeolite Imidazolate Frameworks (ZIFs) Derived Nanomaterials and their Hybrids for Advanced Secondary Batteries and Electrocatalysis

Zeolite imidazolate frameworks (ZIFs), as a typical class of metal-organic frameworks (MOFs), have attracted a great deal of attention in the field of energy storage and conversation due to their chemical structure stability, facile synthesis and environmental friendliness. Among of ZIFs family, the zinc-based imidazolate framework (ZIF-8) and cobalt-based imidazolate framework (ZIF-67) have considered as promising ZIFs materials, which attributed to their tunable porosity, stable structure, and desirable electrical conductivity. To date, various ZIF-8 and ZIF67 derived materials, including carbon materials, metal oxides, sulfides, selenides, carbides and phosphides, have been successfully synthesized using ZIFs as templates and evaluated as promising electrode materials for secondary batteries and electrocatalysis. This review provides an effective guide for the comprehension of the performance optimization and application prospects of ZIFs derivatives, specifically focusing on the optimization of structure and their application in secondary batteries and electrocatalysis. In detail, we present recent advances in the improvement of electrochemical performance of ZIF-8, ZIF-67 and ZIF-8@ZIF-67 derived nanomaterials and their hybrids, including carbon materials, metal oxides, carbides, oxides, sulfides, selenides, and phosphides for high-performance secondary batteries and electrocatalysis.

In-situ growth of MoO2@N doped carbon on Mo2C-MXene for superior lithium storage

Molybdenum dioxide (MoO2) with high theoretical capacity and low cost has triggered extensive interest as a renowned anode for lithium ion batteries (LIBs). However, the sluggish diffusion kinetics and severe capacity decay obstructed its practical application. Herein, hierarchical spherical Mo2C-MXene@MoO2@C was fabricated through a self-assembly and carbonization strategy. DFT calculations and experimental results revealed that the incorporation of metallic Mo2C-MXene and carbon into MoO2 not only modulated the charge distribution and weakened Mo-O bond of MoO2, but also promoted the adsorption of Li+ on MoO2 and lowered the migration energy barrier for Li+, thereby accelerating the electrochemical kinetics, inducing a strong diffusion-controlled charge storage behavior and improving the electrochemical reversibility. In addition, the introduction of MXene reinforced the structural integrity of MoO2 during ion insertion and extraction, which ameliorated the electrochemical stability. Beneficiating from the above synergistic effect, the optimized Mo2C-MXene@MoO2@C delivered remarkable cycling capacity (854.5 mAh g−1 after 500 cycles at 0.5 A g−1) and superior rate capacity (644.4 mAh g−1 at 1 A g−1) for lithium storage. This work disclosed the charge storage mechanism of MoO2 and provided new guidance for the rational design of novel electrode materials for secondary batteries.

P‐Type Redox‐Active Organic Electrode Materials for Next‐Generation Rechargeable Batteries

p‐Type redox‐active organic materials (ROMs) draw increasing attention as a promising alternative to conventional inorganic electrode materials in secondary batteries due to high redox voltage, fast rate capability, environment friendliness, and abundance. First, fundamental properties of the p‐type ROMs regarding the energy levels and the anion‐related chemistry are briefly introduced. Then, the development progress of the p‐type ROMs is outlined in this review by classifying them according to their redox centers. The molecular design strategies employed for improving their electrochemical performance are discussed to guide further research. Finally, a summary of the electrochemical performance achieved, regarding voltage, specific energy with power, and cycle stability, is provided with perspectives.

Template‐Sacrificed Hot Fusion Construction and Nanoseed Modification of 3D Porous Copper Nanoscaffold Host for Stable‐Cycling Lithium Metal Anodes

AbstractLithium (Li) metal anodes have been proposed as a promising candidate for high‐energy‐density electrode materials in secondary batteries. However, the dendrite growth and unstable electrode–electrolyte interfaces during Li plating/stripping are fatal to their practical applications. Herein, the construction of 3D porous Au/Cu nanoscaffold prepared via a convenient template‐sacrificed hot fusion construction method and a nanoseed modification process as an effective Li metal hosting material are proposed. The Au/Cu nanoscaffold can spatially guide uniform deposition of Li metal free from the growth of Li dendrites due to the homogenous Li+ ion flux and negligible nucleation overpotential. Moreover, the Cu skeleton can relieve volume change and stabilize local current density during cycling processes. Benefiting from these advantages, the symmetric cells based on self‐supported Li‐filled Au/Cu (Li‐Au/Cu) nanoscaffold electrodes present highly stable Li plating/stripping for more than 1000 h with a low voltage hysteresis less than 90 mV and a long lifespan over 1300 h at 1.0 mA cm–2 in carbonate‐based electrolytes. Impressively, the Li‐Au/Cu nanoscaffold||LiFePO4 full cells also exhibit exceptional cycling stability and rate performance. This work provides a promising strategy to construct dendrite‐free lithium metal anodes toward high‐performance lithium metal batteries.

Phase relations and electrochemical research for vanadium-based compounds in Li2O–V2O3–P2O5 system

Vanadium-based oxides/phosphates (such as V2O5, Li3V2(PO4)3) are one class of the most important electrode materials for secondary batteries. Herein, phase equilibriums in the Li2O–V2O3–P2O5 ternary system have been studied by means of X-ray powder diffraction to explore new compounds for lithium ion batteries (LIBs). The Li2O–V2O3–P2O5 system can be characterized by the existence of 15 three-phase regions. For the Li2O–V2O3 binary system, it is found that Li3VO4 with high valence vanadium of +5 can stably exist in this system even in the presence of reducing atmosphere during sintering process. Based on this result, the in-situ carbon coated Li3VO4 sample has been synthesized successfully and it shows excellent rate ability and good cycling stability as anode for LIBs. The phase diagram determined in this paper can provide more information about the phase relation of Li2O–V2O3–P2O5 ternary system and serve as a guide for the future investigation of lithium vanadium-based phosphates in this system.

Reduced graphene oxide wrapped sulfur nanocomposite as cathode material for lithium sulfur battery

Sulfur has been investigated as an active electrode material for secondary batteries due to theoretically specific capacity compared to the lithium-ion battery. In the present study, reduced graphene oxide (RGO) sheets wrapped Sulfur nanocomposite (S-RGO) synthesized by hydrothermal method and confirmed the wrapping of RGO sheets on Sulfur nanoparticles by various analytical techniques. The synthesized S-RGO nanocomposite demonstrated improved interaction of sulfur nanoparticles with RGO which is confirmed through XPS analysis. The synthesized S-RGO resulted in significantly improved reversible specific capacity and higher rate capability (823 mAh/g at 0.1C, 400 mAh/g at 1C) with 77 wt% of sulfur loading amount on the cathode of the Li–S battery. Therefore, the present study opens up new insights into sustainable development in the field of Li–S battery energy storage applications.

High-performance aqueous rechargeable potassium batteries prepared via interfacial synthesis of a Prussian blue-carbon nanotube composite

Aqueous rechargeable batteries are sustainable energy storage devices with the potential to replace the current state-of-the-art organic phase secondary batteries. Electrode materials for secondary batteries are often based on composite structures, which combine an electronically conducting scaffold with an ionic conductor, whose properties define battery capacity. Optimal integration of these components can be challenging: here we describe a novel approach to prepare electrode materials based on growth at the liquid-liquid interface. This is illustrated with the synthesis of a carbon nanotube/Prussian blue nanocomposite as free-standing transparent thin films, which are applied as cathodes for aqueous rechargeable potassium batteries. Prussian blue is synthesized through an acid-induced decomposition of ferricyanide, promoted by an interfacial electron transfer from an organic phase donor (1,1′-dimethylferrocene) under ambient conditions. The interfacial synthesis yields selective growth of cubic Prussian blue crystals on the carbon nanotube walls, enhancing interaction between the ionic and electronically conducting components, and resulting in a self-assembled film at the liquid/liquid interface. The films are readily transferred to flexible membranes and applied as cathodes in an aqueous rechargeable K+ battery. Coin-cell devices with activated carbon anodes gave a capacity of 47.6 mAh g−1 at 0.25 A g−1 with an energy density of 33.75 Wh kg−1

Superior "green" electrode materials for secondary batteries: through the footprint family indicators to analyze their environmental friendliness.

As secondary batteries are becoming the popular production of industry, especial for lithium ion batteries (LIBs), the degree of environmental friendliness will gather increasing attention to their products of the whole life cycle. The research combines the life cycle assessment (LCA) and footprint family definition to establish a framework to calculate the footprint family of secondary battery materials. Through the method, we calculated the values of carbon footprint, water footprint, and ecological footprint about this eight kinds of secondary cathode battery materials with Ni-MH, Li1.2Ni0.2Mn0.6O2/C, LiNi1/3Co1/3Mn1/3O2/C, LiNi0.8Co0.2O2/C, LiFePO4/C, LiFe0.98Mn0.02PO4/C, FeF3(H2O)3/C, and NaFePO4/C. When comparing and analyzing their values in each footprint, it can summarize the evaluation method for some secondary batteries by footprint indicators and construct the evaluation system. Through the comprehensive evaluation of footprint family system, the NaFePO4/C battery gets the best performance of three main footprints when combining 1 kg of cathode materials, while Ni-MH is opposite. Hence, among these eight batteries environmental impacts evaluation, the NaFePO4/C battery is regarded as the superior "green" battery, albeit the current application is restricted because of the synthesis limitation on large scale and energy density of storage. In LIBs comparison, the FeF3(H2O)3 material shows its characteristics of environmental friendliness, which is expected to be a greener battery material of LIB. In conventional LIBs, the iron-containing cathode materials show lower environmental burden than ternary cathode materials. We can reduce environmental impacts through developing new advanced materials and reducing the content of high sensitivity element in raw materials.

Crystalline Domain Battery Materials.

The development of next-generation energy storage materials for secondary batteries relies more and more on the delicate design and tailoring of their local structures and properties. Crystalline domain battery materials (CDBMs) are defined as a family of materials that are hierarchically engineered primarily by bonding selective atoms in certain space groups with short-range order to form nanoscale crystal domains as fundamental constructive and functional units, secondarily by integrating these interactive crystal domains under certain configurations into grains to implement electrochemical synergy, and finally by optimizing grains through nanoengineering toward advanced electrode materials. In CDBMs, adjacent crystal domains can undergo structural co-transformations with noticeable interrelationships, and the overall electrochemical performance is determined not only by the intrinsic structure of each crystal domain (element, bonding, valence, stacking, orientation, etc.) but also by the configuration of crystal domains (size, ratio, interface, distribution, interaction, etc.). Pioneering studies have shown significant enhancement of electrochemical performance by controlling crystal domains, suggesting the prospect of developing novel electrode materials through crystal-domain engineering. However, fundamental understanding and delicate fabrication of this material family, in terms of structural identification, electrochemical structure evolution, reaction mechanism, design and adjustment, and structure-performance relationship, among others, still face great challenges to meet the compelling requirements of high-performance electrode materials for secondary batteries. This Account systematically introduces the structure and electrochemistry of CDBMs. The efficient structural identification of crystal domains, which is still challenging due to their structural complexity, is demonstrated using prototype materials by advanced characterization techniques such as high-energy X-ray diffraction combined with Rietveld refinement and spherical aberration-corrected transmission electron microscopy. Investigations on the structural evolution of CDBMs in electrochemical reactions by ex-situ and in-situ techniques provide insights into reaction scenarios such as how ions migrate in and across crystal domains and how these crystal domains transform synergistically. A crystal-domain reaction mechanism is thus proposed to explain the electrochemistry of these materials. Design principles and adjustment strategies for designated crystal-domain structures including their components, ratios, distributions, and interfaces are deduced from the structural identification, evolution and reaction mechanism. The relationship between crystal-domain structures and electrochemical performance can further be elucidated, inspiring us to explore efficient strategies for optimizing the electrochemical performance, as validated by examples of high-performance batteries using materials with controlled crystal-domain structures. Based on these systematic studies, the trends in the rapid enrichment, deep investigation, and practical application of CDBMs are envisioned to promote continuous studies on this nascent energy storage material family.

Semimetal or Semiconductor: The Nature of High Intrinsic Electrical Conductivity in TiS2.

As an intensively studied electrode material for secondary batteries, TiS2 is known to exhibit high electrical conductivity without extrinsic doping. However, the origin of this high conductivity, either being a semimetal or a heavily self-doped semiconductor, has been debated for several decades. Here, combining quasi-particle GW calculations, density functional theory (DFT) study on intrinsic defects, and scanning tunneling microscopy/spectroscopy (STM/STS) measurements, we conclude that stoichiometric TiS2 is a semiconductor with an indirect band gap of about 0.5 eV. The high conductivity of TiS2 is therefore caused by heavy self-doping. Our DFT results suggest that the dominant donor defect that is responsible for the self-doping under thermal equilibrium is Ti interstitial, which is corroborated by our STM/STS measurements.

Symmetric Cell Electrochemical Impedance Spectroscopy of Na2FeP2O7 Positive Electrode Material in Ionic Liquid Electrolytes

Symmetric cell electrochemical impedance spectroscopy (SCEIS) is a powerful method to analyze electrode materials for secondary batteries. The EIS results are used to obtain information related to electrochemical processes such as charge-transfer resistance. In this study, SCEIS is employed to investigate the electrochemical performance of the Na2FeP2O7 positive electrode for sodium secondary batteries operating at temperatures ranging from room to intermediate temperatures using the ionic liquid (IL) electrolytes, Na[FSA]–[C2C1im][FSA] (ILFSA) (C2C1im = 1-ethyl-3-methylimidazolium, FSA = bis(fluorosulfonyl)amide). The obtained SCEIS result for Na metal, acetylene black, α-Al2O3, and V2O5 revealed that the resistance of the high-frequency region in the Nyquist plots is a combination of several factors (the Na[FSA] fraction, ionic conductivity of the electrolyte, and electronic conductivity of the composite electrode). The activation energies obtained by the Arrhenius plots for both the high-frequency and ...

Quinone Electrode Materials for Rechargeable Lithium/Sodium Ion Batteries

AbstractOrganic electrode materials bring about new possibilities for the next generation green and sustainable lithium/sodium ion batteries (LIBs/SIBs) owing to their low cost, environmental benignity, renewability, flexibility, redox stability and structural diversity. However, electroactive organic compounds face many challenges in practical applications for LIBs/SIBs, such as high solubility in organic electrolytes, poor electronic conductivity, and low discharge potential as postive materials. Quinone organic materials are the most promising candidates as electrodes in LIBs/SIBs because of their high theoretical capacity, good reaction reversibility and high resource availability. While quinone electrode materials (QEMs) have so far received less attention in comparison with other organic electrode materials in secondary batteries. In this paper, an overview of the recent developments in the field of QEMs for LIBs/SIBs is provided, emphasizing on the modifications of the quinone compounds in solubility, electronic conductivity, and discharge plateaus. Finally, multifaceted modification approaches are analyzed, which can stimulate the practical applications of QEMs for LIBs/SIBs.

Internal Morphological Evolution of Negative Electrodes Materials in Secondary Alkaline Zn/Ni Batteries

Since the discovery of zinc-based alkaline secondary batteries [1] many investigations were performed on this systems to provide a reliable energy storage device. For example, the Zn/Ni or Zn/Air technologies are excellent candidates in terms of energy-density, power-density and environmental friendliness (they are essentially based on abundant elements, non-toxic materials and processes). Despite their many advantages, the development of alkaline storage technologies is however slowed down by some drawbacks of their negative zinc electrode: dendrite growth, shape change or solubility of zinc discharged products in high concentrated KOH electrolyte, are all responsible for a severe and gradual capacity loss [2]. Intensive research has been conducted concerning anode additives [3–7], to improve performances by reducing those detrimental and consequently non-desirable phenomena. On the one hand, one of the most common used additives is calcium hydroxide, which reacts with zinc oxide during discharge [8,9], and leads to the in situ formation of calcium zincate crystals, following equation (1): 2 ZnO + Ca(OH)2 + 4 H2O ↔ Ca(OH)2,2 Zn(OH)2,2 H2O (1) During this reaction, 4 water molecules are consumed, which can lead to a variation of KOH concentration (and therefore of local pH), especially in starved electrolyte systems, and reduce the battery charge/discharge cycle life. On the other hand, the strategy consisting of directly using calcium zincate as active material instead of adding calcium hydroxide to the zinc oxide electrode has also been developed and investigated. One of the aims was to overcome the problem of non-uniform conversion of calcium hydroxide and zinc oxide into calcium zincate, that occurs during the first few cycles of in situ formation, by improving the distribution of zinc and calcium among the electrode [10]. Another advantage of this strategy is to avoid the electrochemical activation needed to form calcium zincate and the subsequent consumption of electrolyte. It was found [11] that calcium zincate exhibits better electrochemical performance in term of cycle life in comparison with zinc oxide or a mixture of zinc oxide and calcium hydroxide. But the effect is unclear, to date. Indeed, lower solubility of calcium zincate compared to zinc oxides in strong KOH electrolyte shall clearly improve the cycle life of zinc negative electrodes, by drastically reducing the zinc redistribution [8]. In the present study, investigations were undertaken on smalls Zn/Ni homemade Swagelok systems (10 mAh) using negative electrode made using calcium zincate synthesized through hydro-micromechanical synthesis method. Based on a complete set of experimental tools (X-ray radiography, cross section photography, and Scanning Electron Microscopy), the distribution of zinc, calcium and oxygen elements within the electrode was characterized during a prolonged charge/discharge sequence. Relevant electrode degradation mechanism was proposed, a first step towards mitigation strategies of the shape change of the zinc electrode. Fig. Highlighting of zinc segregation inside the thickness of the negative electrode in function of state of charge in Zn/Ni battery [1] T. Michalowski, Improved Secondary or Storage Battery, 15370, 1899. [2] D. Linden, T.B. Reddy, Handbook of batteries, 2002. [3] J. McBreen, E. Gannon, The electrochemistry of metal oxide additives in pasted zinc electrodes, Electrochim. Acta. 26 (1981) 1439–1446. doi:10.1016/0013-4686(81)90015-3. [4] Y. Zheng, J.. Wang, H. Chen, J.. Zhang, C.. Cao, Effects of barium on the performance of secondary alkaline zinc electrode, Mater. Chem. Phys. 84 (2004) 99–106. doi:10.1016/j.matchemphys.2003.11.015. [5] J. Cheng, Z. Zhang, Y. Zhao, W. Yu, H. Hou, Effects of additives on performance of zinc electrode, Trans. Nonferrous Met. Soc. China. 24 (2014) 3551–3555. doi:10.1016/S1003-6326(14)63500-7. [6] F.R. McLarnon, The Secondary Alkaline Zinc Electrode, J. Electrochem. Soc. 138 (1991) 645. [7] K. Bass, P.J. Mitchell, G.D. Wilcox, Methods for the reduction of shape change and dendritic growth in zinc-based secondary cells, J. Power Sources. 35 (1991). [8] R. Jain, E. Division, P. Alto, Development of long-lived high-performance zinc-calcium / nickel oxide cells, J. Appl. Electrochem. 22 (1992) 1039–1048. [9] E.G. Gagnon, Effects of KOH Concentration on the Shape Change and Cycle Life of Zn / NiOOH Cells, Electrochem. Soc. (1989) 1989–1995. [10] A. Charkey, D.K. Coates, Calcium-zincate electrode for alkaline batteries and method for making same, 5,863,676, 1999. [11] J. Yu, H. Yang, X. Ai, X. Zhu, A study of calcium zincate as negative electrode materials for secondary batteries, J. Power Sources. 103 (2001) 93–97. Figure 1

Quinone Based Conducting Redox Polymers for Electric Energy Storage

Conducting redox polymers (CRP), consisting of conducing polymer (CP) and a redox active pendant group (PG) covalently linked to the CP backbone, have been suggested as electrode materials for secondary batteries. This type of material could provide an alternative to inorganic electrode materials and is favorable because of its renewability and sustainability (figure 1). Redox active organic compounds have previously been used as electrode materials for secondary batteries. However, due to the dissolution of many interesting compounds in common battery electrolytes, they suffer from poor recyclability and, in addition, the limited conductivity in these materials requires addition of substantial amounts of conductivity additives in the electrode formulation. By introducing a CP as backbone, not only the dissolution issue is solved, but also the conductivity will be greatly improved. In our studies, we choose polypyrrole as CP, and p-benzoquinone as PG. Polypyrrole has been extensively studied and the electrochemistry and charge transport in this system is well understood. The corresponding knowledge of charge transport in CRPs is however to a large extent lacking. With the aid of temperature dependent in-situ conductivity measurements during the polymer doping process, mechanistic information on the charge transfer in quinone-based CRPs was investigated. Additionally, by varying the link between the two subunits the effect of linker on the performance of the materials was studied. With assistance of various in situ techniques, such as in situ conductivity measurement, in situ ATR-FTIR, EQCM, the interaction between the CP and PG was probed. It was found that the choice of linker has a substantial impact on the charge transport properties of the material. The insight gained from investigating the interaction between these two subunits will benefit further molecular variation of quinone-based electrode materials for secondary batteries. Figure 1